The Turkish military declared its experts had not found traces of explosives on its fighter it claimed shot by Syria, causing confusion and raising questions on Thursday by the Turkish press on how the incident occurred.

"Out of the debris found at sea, no trace of flammable or explosives have been detected," said a statement late Wednesday night by the General Staff of the Turkish Army, adding that of other debris lying in the bottom of the Mediterranean are yet to be explored before reaching a final conclusion.

For the first time, the Turkish army did not use the term "shot by Syria" but preferred to speak about "our airplane claimed to be destroyed by Syria," causing some confusion on how the incident, which heightened the crisis between Turkey and Syria, has really happened.

Until now, the Turks insisted that Syria shot down on June 22 one of their F-4 Phantom planes while on a training mission in the eastern Mediterranean. Both pilots were killed.

Damascus has acknowledged destroying the aircraft, accusing it of violating its airspace.

On Thursday, the Turkish press questioned the military statement on the consequences of the incident, raising a possible theory that accident caused by a pilot error or technical failure led to its crashing, without totally excluding a hostile act.

A former army general of the Turkish Air Force, Erdogan Karakus, interviewed by the Hürriyet newspaper thinks it could be an accident. "We can not say exactly what happened as the fuselage of the aircraft has not been studied but Turkey seems to change its thesis," he told the newspaper.

According to another expert interviewed by the Milliyet daily, an anti-aircraft reportedly exploded near the aircraft and might destabilize it and caused to its crash.

Meanwhile, the UN Security Council is discussing a new draft resolution on Syria. In the text that will be discussed Thursday, Europeans and Americans give to President Assad's forces 10 days to withdraw its troops from rebel towns, under penalty of additional economic sanctions.

The resolution was prepared by the United States, France, the UK and Germany. It refers to Article 41 of the UN Charter, which provides for diplomatic and economic sanctions, such as an embargo, but not military intervention. The resolution also extends for 45 days the Mission of UN observers in Syria (Misnus), whose term expires July 20. Russia had proposed a resolution which also renews the mandate but does not mention sanctions.

International envoy Kofi Annan on Wednesday stated he would ask the Security Council to intensify pressure on the Syrian regime. The international mediator, who has just completed a tour in Damascus, Tehran and Baghdad, said that Iran and Iraq continued to support his six-point plan adopted by the Council in April and not applied in the field.

On the ground, the violence does not stop. On Wednesday at least 52 people were killed across the country after 82 were killed Tuesday.